At its height, a warning was in effect for more than 3,000 miles of coastal
zones north of the Washington border: British Columbia and Alaska’s entire
southern shoreline including the Aleutian Islands. The National Weather
Service sent messages to cellphones in Alaska with the message: “Emergency
Alert. Tsunami danger on the coast. Go to high ground or move inland.”

“Based on all available data a tsunami may have been generated by this
earthquake that could be destructive on coastal areas even far from the
epicenter,” the Pacific Tsunami Warning Center said.

An announcer on KMXT radio in Kodiak appealed for residents to heed the
warning. Many did. A line of cars clogged a snow-covered road heading out
of town.

“This is not a drill. Please get out to higher ground,” said the message.
“If you are on the flats, get up on one of the hills . . . Just go high.”

The National Tsunami Warning Center in Palmer, Alaska, put out an updated
alert that canceled the warning for most of the West Coast.

Alerts in the following areas have been canceled because
additional information and analysis have better defined the
threat.

* The Tsunami Watch is canceled for the coastal areas of
California, Oregon and Washington from The Cal./Mexico
Border to The Wash./BC Border

* The Tsunami Warning is canceled for the coastal areas of
British Columbia, Southeast Alaska and South Alaska and the
Alaska Peninsula from The Wash./BC Border to Hinchinbrook
Entrance, Alaska (90 miles E of Seward)

* The Tsunami Warning is canceled for the coastal areas of
South Alaska and the Alaska Peninsula and Aleutian Islands
from Chignik Bay, Alaska to Attu, Alaska

For other US and Canadian Pacific coasts in North America,
there is no tsunami threat.

Plenty of Twitter accounts worked feverishly to relay the message.

The #tsunami warning is canceled for the coastal areas of British Columbia and #Alaska from WA/BC border to Hinchinbrook Entrance, AK, per JTWC. A tsunami was generated but does not pose a threat to these areas. #akwx

Twitter amplifies offline communication modes, as well. Emily Kwong, with
Raven radio, tweeted that the loudspeakers used to broadcast alerts were
now spreading the all-clear.

Chimes going off in Sitka, Alaska, as booming emergency voice sounds the all clear: "Repeat. The tsunami warning has been canceled. It is safe to return to coastal areas." City says school will happen today. Kids I've spoken with have mixed feelings about that. #Tsunamipic.twitter.com/BVK3005WfJ

Others pointed out that the alerts proved the tsunami detection and warning
system worked:

.@mikefarnworthbc has released a statement in light of the #TsunamiWarning being cancelled. Says this event "demonstrates that coast warning systems do work." Also reminding people not to call 9-1-1 for info on the tsunami, 9-1-1 only for emergencies. #bcpoli#bcgov

The swift alert cancellation helped emergency services to maintain
credibility with its audience.

The tsunami-related alert and retraction stand in stark contrast to the
mishandled emergency warning in Hawaii on Jan. 13 that advised residents to
prepare for an incoming missile. The resulting panic lasted nearly 40 minutes, until that erroneous message
was rescinded.